Beitzah 13: Is Eating-on-the-Go Not Holy?

Terumot and maaserot - the holiness that is in the food, and how to handle it. Including how the foods themselves are usually prepared for eating. Plus all kinds of food prep for yom tov. Also, fixing the amounts of these gifts - must the amounts be precise? Or approximate? Terumah, ma'aser, and terumat ma'aser are treated differently.